<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body {
            padding: 0;
            margin: 0;
            background-color: skyblue;
        }

        .dialog {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            width: 200px;
            height: 100px;
            background-color: #fff;
            text-align: center;
            line-height: 80px;
            font-size: 20px;
            color: #3c3c3c;
            text-transform: uppercase;
            letter-spacing: 3px;
            clip-path: polygon(0 0, 100% 0, 100% 80%, 90% 80%, 80% 80%, 70% 80%, 0 80%);
            transition: all .5s;
        }

        .dialog:hover {
            clip-path: polygon(0 0, 100% 0, 100% 80%, 90% 80%, 90% 100%, 70% 80%, 0 80%);
        }
    </style>
</head>
<body>
<div class="dialog">dialog</div>
</body>
</html>